The present invention relates to paving screeds, and more particularly to controllers used with systems for heating paving screeds.
The quality of an asphalt mat is affected by the temperature of the asphalt material during the paving process. One method for ensuring that the asphalt is at a sufficiently high temperature is to use a heated screed, such that thermal energy (i.e., heat) is transferred from the screed to the asphalt while the material is being leveled by the screed. Systems for heating a paving screed include one or more heaters located inside the housing of the screed and configured to transfer thermal energy to the screed plate (the portion of the screed that actually levels the asphalt). Such heating systems include gas burners, usually for diesel or propane gas, in combination with xe2x80x9cblowerxe2x80x9d fans, electrical resistance heaters, etc.
In general, the control of such screed heating systems is merely a simple xe2x80x9con-offxe2x80x9d switch that requires the screed operator to start the heating system and then the system operates until such time as the operator decides to shut the system off. If the operator does not properly monitor the temperature of the screed, excessive heating of the screed, causing poor asphalt mat finish or damage to the screed components. Further, if the screed operator shuts down the heating system and then forgets to re-start system, the quality of the asphalt mat is diminished due to leveling with a xe2x80x9ccoldxe2x80x9d screed.
Therefore, it would be desirable to have a controller for a paving screed heating system that operates safely and ensures that the heating system does not over-heat or insufficiently heat the screed.
The present invention is controller for a heating system of a paving screed including a screed plate. The heating system is connected with the screed and is configured to transfer thermal energy to the screed plate. The heating system 1 further includes an actuator 16 configured to adjust thermal energy output of the heating system. The controller comprises a temperature sensor connectable with the screed and configured to sense temperature of the screed plate. The sensor is also configured to generate electrical signals proportional to sensed temperature. Further, an electrical logic circuit is electrically connected with the sensor and electrically connectable with the actuator. The logic circuit is configured to compare a temperature signal from the sensor with a desired temperature value and to automatically operate the actuator such that the actuator adjusts thermal energy output of the heating system so as to maintain the screed temperature about the desired temperature value.